An earth bolt is used for both fastening an electric device to a body structure of an automobile or the like and electrically connecting the electric device to the body structure.
A fastening method using a conventional earth bolt needs the following steps and cost.
The method removes part of a coating on a frame and attaches an earth plate with a bolt. Another method of connecting an earth terminal to a flame with a bolt having a notched screw thread scrapes the coating off by screwing the bolt into an internal screw thread formed in the frame.
When such a conventional earth bolt is used, the following problems arise. Work for removing the coating and masking parts needs man-hours and deteriorates workability. Use of the earth terminal, a wire and a plate increases the cost. In most cases, several fastening bolts are used, which increase the cost still further.
The conventional method of attaching an electric device to a body structure of an automobile or the like fastens the electric device to the body structure such that the electric device is electrically connected to the body structure and the joint of the electric device and the body structure is watertight. A method mentioned in JP 2009-246740 A electrically connects an electric device to a body structure by pressing a pad serving as a grounding electrode against the body structure and ensures a watertight joint by preventing water infiltration with a ridge not for electrical connection.
Patent Document: JP2009-246740A